I tow a Smart - Great Tow Veh with. Blue Ox Hitch. Hardly know it is there from a performance perspective. While I have a Ready Brake, I don't think the toad brake is necessary to meet regulatioms. SMART weighs about 1840 lbs. I tow it behind a Leisure Van Libero B+. I tried stopping distance tests @ 20, 30 & 50 mph with and without the brake connected. While I was able to stop in a shorter distance with the brake on, I met the stopping distance requirement per CA stopping distance without the brake connected.
I owned big rigs for years, my last one was a 40ft Monaco Dynasty and I towed several different toads the last one being a Malibu Max. I used a Master Brake air actuated actuated that gave proportional braking which Ready brake does not.
When it comes to safety, more braking is better than less, regardless of any regulation.
Well that is my 2 cents worth of thought and SMART is a smart choice for a Toad with or without a braking system.